1. Field of the Invention
The present invention generally relates to measurements systems, and more specifically to a potentiometer providing high resolution.
2. Related Art
Potentiometer generally refers to a device/component which provides variable resistance. In a typical scenario, a user specifies a desired resistance, and the potentiometer provides the specified resistance. Examples of situations in which potentiometers are used include radio tuning, television brightness control, regulator of a fan, etc.
Potentiometers are often characterized by resolution. Resolution refers to the minimal change in resistance that can be offered by (or attained by using) a potentiometer. For example, a resolution of 0.1 ohm implies that a change of 0.1 Ohm can be reliably attained from a previous resistance value. In other words, it may not be possible to reliably attain a resistance change of less than 0.1 Ohm. It is often desirable that potentiometers provide high resolution, i.e., ability to change resistance by a small value.
An analog potentiometer is often employed to provide such high resolution. A typical analog potentiometer contains a resistor which can be tapped at different points to attain a corresponding resistance. As the tap points can potentially be contiguous (or with extremely small distance in between), a correspondingly high resolution can be attained.
However, one problem with analog potentiometers is that tapping at different points generally requires use of mechanical components. Non-manual approaches to attaining precise movement (and thus the desired precise resolution) often presents technical challenges, thereby making it generally undesirable for use in electronic/electrical systems, as is well known in the relevant arts.
Digital potentiometers overcome some of such disadvantages. Digital potentiometers often contain digital switching elements (e.g., transistors) which are operated to connect only some of the available resistors to provide a desired resistance value. As an illustration, one prior digital potentiometer contains discrete resistors providing equal resistance connected in series, and a digital circuit includes a number of resistors corresponding to a specified resistance between output terminals. For example, a digital potentiometer may contain 10 resistors each providing 100 ohms resistance, and 4 of the resistors may be connected between output terminal assuming that the specified resistance equals 400 ohms.
Digital potentiometers are suitable for integration into electrical/electronic environments since the switching elements can be implemented at least substantially using only electronic/electrical technologies. However, one problem with digital potentiometers is that the available resolution is often low (compared to analog potentiometers). In the illustrative example of above, the digital potentiometer provides a resolution of 100 ohms. At least in some environments it may be desirable to provide potentiometers which provide the advantages of digital potentiometers, and yet offer higher resolutions.